italianartsociety:

Researchers have announced a new understanding of Roman concrete – a versatile artificial stone that allowed Roman builders to create magnificent, open interiors of unprecedented scale. Collaborators used X-ray beams to study samples under the auspices of the Lawrence Berkeley National Laboratory to understand better why Roman concrete does not crumble and how monuments like the Pantheon, Colosseum, and Markets of Trajan stand to this day. Not only does this research enhance our comprehension of ancient building practice but also it offers hope for more environmentally friendly methods today.

Roman concrete uses a volcanic ash-lime mortar that is virtually crack-resistant combined with chunks of volcanic stone and other materials, often brick. Today’s concrete is made with limestone-based Portland cement, which requires a temperature of 1,450C (2,642F) to create and releases upwards of 7% of the world’s carbon emissions annually. Roman concrete, by contrast, does not require such high heat and could lead to the development of greener concrete through the use of volcanic material as the Romans did over two millennia ago. 

Pantheon, 118-128 CE, Rome, aerial view

Sample of Roman concrete. Photo by Roy Kaltschmidt, Berkeley Lab

Colosseum, 70-80 CE, supporting concrete vaults, Rome

Trajan’s Markets, 100-110 CE, distant view and vaults of great hall, Rome